In a treasonous manner, or to a treasonous degree(adverb)
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Use "treasonously" in a sentence
"The implication, whether intentional or not, is obvious: the shadowy advertisers either want Obama to be framed for high crimes and misdemeanors he did not commit, “Impeach” is simply a euphemism for “treasonously overthrow.”"
"He would treasonously expose a CIA agent for political gain."
"It's Obama whose legacy will be a 9 trillion dollar deficit, but he couldn't have achieved that with a lot of help from treasonously irresponsible tax-and-spenders like Ted Kennedy."